Progress in unsteady converging shock reflection and refraction

Unsteady shock reflection and refraction have become increasingly attractive in recent yearsdue to their significance in scientific and engineering areas. The unsteady phenomena of a planar shock wavereflecting over a curved wedge have been investigated. During this process, the shock intensity is unvaried whilethe incident angle keeps changing, which results in the transition between different wave patterns. When a curvedshock wave moves along a solid wall or an interface separating two different fluids, both the shock intensity andincident angle are changing, which probably have significant influences on wave patterns and their transitions.Nevertheless, it is a difficult problem to create a curved shock wave with regularities in laboratory. Based onshock dynamics theory, Zhai proposed a method to transform a planar shock wave into a cylindrically convergingone, and the investigations on reflection of a converging shock wave at a solid wall and on the refraction of aconverging shock wave at a fluid interface were carried out. In this work, the progress in unsteady cylindricallyconverging shock wave reflection and reflection phenomena in our laboratory has been discussed, focusing on theeffects of incident angle and flow unsteadiness on wave patterns transitions. Finally, we propose the following issuesfor future study.